Periodic Reporting for period 3 - NEWTON-g (New Tools for Terrain Gravimetry)
Reporting period: 2020-12-01 to 2022-11-30
The main reason why gravimetry is still a largely underexploited technique is related to the characteristics of available gravimeters that are very expensive and not well suited for continuous measurements in out-of-the-lab conditions.
NEWTON-g proposes a radical change of paradigm for gravimetry. The project aims at developing a field-compatible gravity imager (Fig. 1), able to real-time monitor the evolution of subsurface mass changes. This system includes an array of low-costs MEMS relative gravimeters, anchored on an absolute quantum gravimeter; it is meant to provide imaging of gravity changes with unparalleled spatio-temporal resolution.
The relatively low-cost of the MEMS devices will democratize the gravimeter industry by making the necessary technology affordable, thus vastly increasing the number of potential users.
NEWTON-g aims at field-testing the gravity imager at Etna volcano (Italy), where data from the new devices will be validated against data provided by standard instruments in the permanent monitoring system.
The general rules for accessing NEWTON-g’s data and issues concerning the availability, exchange, use and maintenance of the data were discussed in D1.1 while implementation of the principles set out in D1.1 was addressed in D1.2.
During RP1 the project logo and website were published (D5.1) the kick-off workshop was organized (D5.2) the dissemination and exploitation plan was released (D5.3) and the project video was produced (D5.4).
During RP2 (month 13 to 30), the activity concerned (a) the validation of the design of MEMS (D2.2) and quantum (D2.3) gravimeters; (b) the preparation of the plan for the deployment of the gravity imager (D3.2); (c) the production of the first prototypes of MEMS and quantum devices and the validation of their performances (D2.4 and D2.5); the design and development of the field infrastructures (D3.3); the development of software tools to handle and interpret the data produced by the gravity imager (D4.2 and D4.3); the deployment of the new measurement system at Mt. Etna (D3.4).
The breakout of the COVID-19 pandemic severely affected the project implementation as of March 2020 (month 22).
During RP2, a paper focused on the rationale and objectives of NEWTON-g was published (Carbone et al., 2020).
During RP3 (month 31 to 54), activities carried out under NEWTON-g included (a) completion of the field deployments with the installation of 4 MEMS gravimeters at Mt. Etna (D4.4); (b) evaluation of the performance of the AQG-B installed at Mt. Etna in 2020 (D4.4 and Antoni-Micollier et al., 2022); (c) development of new analytical solutions to calculate the deformation-induced gravity changes caused by triaxial sources (D4.5; Nikkhoo and Rivalta, 2022; 2023); (d) study of gravity anomalies recorded at Mt. Etna, with a view to exploring the potential of gravity data for volcano hazard analysis (D4.5).
We fully demonstrated that the AQG-B provides continuous gravity data suitable for volcano monitoring purposes. Building on the successful application at Mt. Etna, other agencies and research institutions have either acquired an AQG-B, or demonstrated interest to acquire one of this devices in the future. This represents the achievement of one of the objectives of NEWTON-g, i.e. shifting the production of gravimeters for geophysical applications from North America to Europe.
Even though, mostly because of COVID-19-related delays, it was not possible to make the original idea of “gravity imager” came completely true, we performed field tests with the MEMS gravimeters that have provided crucial information for further upgrades.
The new analytical solutions, developed in the framework of WP4, fill a recognized gap in volcano geodesy and will make the joint analysis and inversion of ground deformation and gravity data easier and more accurate.
The data produced under NEWTON-g have been integrated within the EIDA archive, an infrastructure compliant with the FAIR principles.
Finally, several papers were published in peer-reviewed journals during RP3, where results from different project activities are presented.
The core objective of the NEWTON-g consists in advancing the hardware for gravity measurements beyond the current state-of-the-art.
NEWTON-g aims at developing the world’s first field versions of MEMS relative and quantum absolute gravimeters. We have already validated the design of both devices, thus setting the first stepping-stone beyond the state-of-the-art.
Another important objective of NEWTON-g involves the development of the gravity imager and its deployment at Etna, where its performances will be validated against standard instrumentation in the monitoring system of the volcano. The achievement of this objective will lead to a paradigm shift in gravimetry. The design of the gravity imager has also been validated during the first reporting period of NEWTON-g, which makes another important advancement beyond the state-of-the-art.
Expected results until the end of the project
By the end of the project we expect to demonstrate that the newly developed MEMS and quantum gravimeters can operate under harsh field conditions and measure the gravity acceleration to a suitable level of precision. NEWTON-g will drive the development of a new generation of gravimeters and the field-test at Etna will foster the application of the new sensors also in domains other than volcanology, including hydrology, geodynamics, reservoir monitoring, oil, gas and mineral prospecting.
Furthermore, we aim to demonstrate the potential of the gravity imager. It will be the first time an array of several continuously recording gravimeters is deployed in a single area, allowing imaging of sub-surface fluid dynamics to be achieved with unprecedented time and space resolution. The final validation of the gravity imager will be the real-time direct observation of volcano-related gravity changes through an extended array of gravimeters, a world’s first!
Potential impacts
We expect that the development of the new gravimeters will broaden the use of gravimetry, making it much more popular.
Once the capabilities of the gravity imager are demonstrated, we expect that the new gravimeters will be deployed as an array of continuously running devices at other volcanoes worldwide. NEWTON-g will thus help to take a step forward in volcano monitoring, through opening a new window for hazard assessment.
We also expect that the methodology and workflow of NEWTON-g will be applied to domains other than volcanology. For example, reservoir monitoring (water, oil or gas) could benefit from the results obtained within NEWTON-g, towards a more sustainable management of underground resources.